It was the last day of the final examination in a university. A group of students entered the classroom happily. This was their last exam. They knew it wouldbe easy. The professor had said that they could bring any book or note they wanted. The only requirement(要求) was that they couldn't talk with each other. The professor handed out the papers. They were glad to find there were only five questions. Three hours passed. The professor asked, How many of you have finished all the five questions? None of the students answered.How many of 3'ou have finished four? No answers again.Thee? Two? The